Parkinson's disease (PD) is associated with pathological increases in iron and 1-synuclein (1-syn) in the substantia nigra (SN), and these features are reproduced animal models of PD that use the pesticide rotenone. Both 1-syn and iron accumulate in nigral dopamine neurons and are cytotoxic; however, the mechanism underlying their pathological accumulation is unknown. We have identified a transferrin/transferrin receptor 2 (TfR2)-mediated mechanism for iron accumulation in nigral dopamine neurons, and have found that TfR2 levels are increased in dopamine neurons in the rotenone rat. GATA transcription factors, whose role has been well characterized in hematopoiesis, have recently been shown to positively regulate the expression of 1-syn in vitro. The isoform GATA2 is expressed in human SN, and preliminary studies have localized GATA2 to dopamine neurons in rat SN. Preliminary data indicate that GATA2 positively regulates TfR2 transcription in vitro. Thus it is possible that GATA2 positively and coordinately regulates both 1-syn and TfR2 in nigral dopamine neurons in vivo, and that therapeutic GATA2 inhibition may simultaneously ameliorate the deleterious effects of both 1-syn and iron in PD. This proposal will use in vivo viral-mediated gene silencing in rat SN to test the following hypotheses: 1) GATA2 regulates 1-syn and TfR2 in rat nigral dopamine neurons, and 2) inhibition of GATA2 in nigral dopamine neurons leads to decreased accumulation of 1-syn and iron following rotenone treatment, thereby attenuating nigrostriatal degeneration. This work will examine how two apparently disparate pathological features of PD-the accumulation of 1-synuclein and the accumulation of iron within nigral dopamine neurons-may be coordinately attenuated via inhibition of the transcription factor, GATA2, using in vivo viral-mediated gene silencing. Successful completion of these aims would establish GATA2 as a potential therapeutic target that could be exploited using gene therapy to ameliorate the cellular toxicity associated with both 1-syn and iron accumulation in human PD.